Resurfacing hip prostheses revisited: failure analysis during a 16-year follow-up.

We conducted a prospective study of the clinical and radiographic variables related to the survival of 114 cementless resurfacing double-cup hip replacements (RHR) with a mean follow-up of 9 (range: 1--16) years. Three patients died, and 22 were unavailable for the final review in 2003. Sixty-one RHRs had to be revised to a total hip replacement. Failure analysis of these revised RHRs showed femoral head and neck resorption under the prosthesis in 33, acetabular protrusion in seven, both femoral and acetabular resorption in 14 and a femoral-neck fracture in three. One hip had dislocated, and there were three hips with unexplained pain. The Kaplan-Meier 5-year mean survival was 92%, the 10-year survival was 47% (95% CI 37--57%) and the 15-year survival was 30% (95% CI 20--40%). Pre-operative joint destruction (grade 1), a high degree of radiological osteoporosis, a body mass index >25 and prosthesis mismatch were significantly related to failure of the RHR. We believe that in young, non-obese patients with pre-operative radiological central destruction but without severe proximal femoral osteoporosis, a resurfacing arthroplasty may have some value. Our failures were mainly due to femoral resorption under the prosthetic femoral component.